On-Line Training Program
Module 4b
How do AGV Systems Work?
AGVS Product Section
of
MHI
© 2012 MHI®. All rights reserved.
Summary
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Host computer/Server
Graphical user interface
Communication (RF, IR, Wire, etc)
Order creation
Traffic control
Charging
Integration into facility hardware (doors,
conveyors and the like) and software (WMS,
WCS, and the like)
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
System components
Operator interfaces
System controller
AGV
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Host system
OPC IO
Common system functions
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Order handler
AGV handler
Traffic handler
Digital I/O handler
Communications – AGVs and other units
Simulator
Gather statistics
Generate reports
Diagnostics
System visualization
Backup and redundancy
Black box / “Flight” recorder
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Server
• Usually PC based
• Network connected
• Database backend
• Backup
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Graphical user interface
• Desktop, laptop or mobile device
• Graphical overview of the system
• Tracking of AGVs
• Visualization of peripheral I/O units (OPC)
• Event logs
• Order buffer
• System health
• Statistics and reports
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Server connectivity
• Connected to the AGVs through
• Wireless network
• Radio
• Connected to other systems through
• Ethernet
• I/O
• Utilizes OPC
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Basic communication with AGVs
Server
Traffic and order control
Command to a location and perform an operation
Vehicle position & status
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Flexible I/O with OPC
 Server can connect to an OPC server.
 OPC supports a number of field bus standards:
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CAN bus
Profibus
Interbus
Devicenet…..
 Read about the standard at: www.opcfoundation.org
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Layout
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Layout
 Defined drive paths, where the AGVs are
allowed to drive.
 Divided into segments/tracks and points
– The points are valid targets
– The segments are parts of the drive paths
 Some systems use stations where load
operations are allowed
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Layout-less systems
 Some systems run without a layout created in
a definition tool
 These systems are typically based on magnetic
tape or wire guidance
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
System Control
 Choose best AGV for transport
 Routing; Choose best path
 Manage blocking
– Other AGVs in the drive path
– Stationary equipment (automatic doors, stretch
wrappers and the like)
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Traffic rules - Blocking
• To maximize the movement of AGVs, there must be a set of
rules that meters the flow of AGV traffic and eliminates the
potential for traffic jams. This is often called blocking.
• Before the AGV is allowed to drive on the calculated path, it
is checked to make sure that the path is free using the traffic
rules set up for the system. The path, or a suitable part of
the path, will then be allocated to that AGV.
• Auxiliary blocking will control the AGV as it interacts with
external objects (doors, active machines, and the like). This
is achieved by interacting with the objects through OPC or
other I/Os.
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Traffic decision points - Blocking
 A second approach to blocking involves
decision points or tags
 Every time an AGV passes a tag, a script is run
to evaluate the traffic situation and
destination before acting accordingly
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Order handler – Manages order assignment to AGVs
 Simple transports
– Move container from location A to location B
 More complex multi-part order - Pick order
– Move AGV through warehouse while operator manually
places goods on the pallet. Automatically moves AGV to
finish point when complete. Automatically deploys new
AGV when needed.
 Charging
– Move AGV to charger when AGV is idle or needs power
and charger is available.
 Idling
– Manages AGVs that have no order
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Order
• An order defines one or several movements, to be
executed by the AGV
• A typical order contains a pick-up-location and a dropoff-location
• When used in a pick application, an order may contain
several stops, where items are manually added to AGV
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Charging
• An automatic order for an AGV to go charge can be
generated by the system
• Low voltage may trigger a charge
• Opportunity charging may also be used based on:
• AGV being idle
• AGV being close to a charger
• Other customizable triggers
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Programmability
• PLC or scripts on system level
• Customized logic
• Events and alarms
• Debugging
• Interaction with host systems
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Host Integration
• AGV orders are commonly initiated by a host system
such a WMS, WCS, MES or ERP (*)
• Standard or custom interfaces are defined for the host
system to start orders, move AGVs and other tasks
• Integration options include standards such as SQL
databases, message queues (MQ), Web services, FTP,
TCP/IP sockets and more
* WMS = Warehouse Management System, WCS = Warehouse Control System, MES = Material Execution System, ERP = Enterprise Resource Planning system
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
Handling of Idle AGVs
• Home location
• A home location is a place where the
AGVs go when not executing orders.
• Queues, parking and intermediate locations
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
AGV Allocation
• The best AGV for a specific order may be selected
by the system manager
• Host systems may select an AGV for an order
• AGVs can manually be selected
8720 Red Oak Blvd., Suite 201 | Charlotte, NC 28217-3992 USA
Phone: (704) 676-1190 | FAX: (704) 676-1199
For More Information:
Contact the
AGVS Product Section
of
MHI
http://www.mhi.org/agvs
© 2012 MHI®. All rights reserved.